This invention relates to a tape reel for use in a cassette video tape assembly.
Generally, the cassette video tape assemblies are designed so that the tape will usually have to be unwound or rewound in a slightly oblique position. When the tape reel continues to be maintained in a horizontal position, therefore, an immoderate force is exerted on the tape being unwound or rewound. To preclude this adverse effect, it becomes necessary for the tape reel itself to be inclined obliquely to an angle proportionate to the unwinding or rewinding angle of the tape. It is imperative on the other hand that the tape reel, even while it is held in an inclined position as described above, should maintain safe engagement with the reel spindle.
At the time that the tape reel is set in position within the cassette housing, therefore, since the rebound piece in the form of a leaf spring disposed on the cover of the housing comes into point contact with the small protuberance formed at the center of the upper flange of the tape reel and the reel spindle is set in position and carried on the lower flange of the tape reel, the tape reel set in the housing is allowed to be inclined to a certain degree. Further since the resilient rebound piece keeps the tape reel pressed downwardly through the medium of the small protuberance, the inclination of the tape reel causes the reel neither to rise from its fixed position nor to produce any play during its rotation. Consequently, the tape reel is allowed to safely retain its fast engagement with the reel spindle.
As may readily be inferred from the construction described above, the friction between the small protuberance and the resilient rebound piece continues so long as the tape is in motion and this continued friction occurs as frequently as the cassette video tape is put to use. For protection against possible abrasion, therefore, the small protuberance is required to be made of a material which specifically excels in rigidity and resistance to abrasion. The material is also required to be excellent in dimensional accuracy. This is because the reel rotates with uneven motion or with vibration when the tip of the small protuberance fails to fall on the true axis of the reel.
The resilient rebound piece is made of a suitable metal to ensure ease of its fabrication and perfection of its function. Similarly, to facilitate easy fabrication, the tape reel is made of a synthetic resin. The material which best satisfies the various conditions the small protuberance is expected to fulfil is polyacetal. Unfortunately, resinous materials of the class excelling in wear resistance, rigidity and dimensional accuracy turn out to be extremely expensive. In spite of the high cost, tape reels of the conventional construction must use expensive material not merely in the small protuberance but also in large amounts for other adjacent parts which do not particularly require the properties of an expensive resin, solely because the small protuberance necessitates use of that particular material. The use of large amounts of expensive material is indispensable because the major factor in reducing the cost of tape reel manufacture lies in the reduction of the number of component parts used and the number of work steps involved in the reel assemblage.
The upper flange of the tape reel is made of a transparent resin in order that the user may freely observe the tape being unwound out of or rewound on the reel disposed under the flange. Since polyacetal and other similar resins possessed of high wear resistance are generally opaque, it has not been possible to use the simple expedient of molding the small protuberance at the center of the upper flange as an integral part thereof.
An object of this invention is to provide a tape reel for a video tape cassette which, in view of the aforementioned true state of affairs, is directed to minimizing the consumption of the expensive material and consequently lowering the cost of production.
Another object of this invention is to provide a tape reel which can be manufactured by following, to the fullest possible extent and without any complication, the simplest procedure of assemblage heretofore practiced in the art.